Japanese patent 3832730 (Reference 1) discloses, as a technique relevant to the above-mentioned valve open/close timing control system, the constitution is disclosed where a driven-side rotating member (first rotating member (rotor) in Reference 1) is fitted into the inside of a drive-side rotating member (second rotating member in Reference 1). Reference 1 also discloses the constitution where a locking body is provided in an extendable and retractable manner from an inner periphery of the drive-side rotating member to a locking oil passage formed on an outer periphery of the driven-side rotating member, and a spring which biases the locking body in the projecting direction is provided.
Reference 1 discloses the constitution where locking of the locking body is released by a centrifugal force along with the rotation of a valve open/close timing control device, and also discloses a control mode where locking is released by supplying working oil to the locking oil passage before a rotational speed reaches a speed at which the locking body is released by a centrifugal force at the time of starting an internal combustion engine (engine in Reference 1).
International Publication WO2011/055589 (Reference 2) discloses the constitution where a plurality of fluid pressure chambers are formed on an inner peripheral side of a drive-side rotating member, a driven-side rotating member is fitted into the inside of the drive-side rotating member, and each fluid pressure chamber is partitioned by a vane mounted on an outer surface of the driven-side rotating member in a projecting manner thus forming an advanced angle chamber and a retarded angle chamber in each fluid pressure chamber. The constitution disclosed in Reference 2 also includes an intermediate locking mechanism which restrains a relative rotational phase between the drive-side rotating member and the driven-side rotating member to an intermediate locking phase which is positioned between a most advanced angle and a most retarded angle, and a most retarded angle locking mechanism which restrains the relative rotational phase at a most retarded angle phase at which the relative rotational phase becomes a most retarded angle.
Reference 2 discloses the constitution where the intermediate locking mechanism includes a groove-shaped intermediate locking groove formed on an outer periphery of a driven-side rotating member, and a pair of intermediate locking members which is mounted on a drive-side rotating member in an extendable and retractable manner, and a relative rotational phase is restrained to an intermediate locking phase by making both intermediate locking members simultaneously engage with the intermediate locking groove at both end positions. Reference 2 also discloses the constitution where the most retarded angle locking mechanism includes, besides the intermediate locking mechanism, a most retarded angle locking groove formed on an outer periphery of the driven-side rotating member and a most retarded angle locking member which is supported on the drive-side rotating member in an extendable and retractable manner, in which the relative rotational phase is restrained to a most retarded angle phase by making the most retarded angle locking member engage with the most retarded angle locking groove.
To consider a control mode of a hybrid-type vehicle, an engine is stopped in the case where a battery is sufficiently charged, and an engine is started in the case where a discharge amount of the battery exceeds a predetermined value and in the case where a traveling torque is insufficient and an assist is necessary. Accordingly, start and stop of the engine are frequently performed due to such a control.
Further, in starting an engine in a hybrid-type vehicle, for the purpose of suppressing vibrations of the engine at the time of starting the engine, an attempt has been made to reduce (suppress) a compression ratio of the engine using a valve open/close timing control device. However, startability is lowered when a compression ratio is reduced and hence, under a present situation, the ignition of a gas mixture in an engine is performed after a rotational speed (the number of rotations per a unit time) of the engine is elevated to a high value (approximately 800 to 1200 rpm).
On the other hand, when an engine is started at a compression ratio suitable for starting in a general-type engine, the engine is started with a rotational speed of a crankshaft set at a relatively low value (approximately 100 to 300 rpm). In this case, power consumed by a starter motor for rotating a crankshaft is not so large. To the contrary, however, in a control where the engine is started in a state where a compression ratio is reduced as described above, it is necessary to elevate a rotational speed of the engine to a high value as described above and hence, electric power of a battery is wastefully consumed thus shortening a traveling distance. Accordingly, there is a room for improvement with respect to such a control.
A need thus exists for a valve open/close timing control system which can reasonably prevent the wasteful power consumption at the time of starting an internal combustion engine.